Nanostructure formation device using microwaves

ABSTRACT

The present invention relates to a nanostructure formation device using microwaves and, more specifically, to a novel structure of a nanostructure formation device using microwaves, the device being capable of introducing a solution process factor to a conventional nanostructure formation device using microwaves, so as to stably manufacture a nanostructure by using a microwave while consistently maintaining the concentration of a formation solution and the process conditions for it when the nanostructure is formed through a solution process.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a nanostructure formation device usingmicrowaves and, more specifically, to a novel structure of ananostructure formation device using microwaves, the device beingcapable of introducing a solution process factor to a conventionalnanostructure formation device using microwaves, so as to stablymanufacture a nanostructure by using a microwave while consistentlymaintaining the concentration of a formation solution and the processconditions for it when the nanostructure is formed through a solutionprocess.

Related Art

Ongoing research is currently being conducted to make semiconductordevices, optical devices, and memory devices by using nanomaterials'unique electrical, optical, and magnetic properties. To construct adevice using nanomaterials, it is essential to employ a technology forgrowing nanomaterials where they are needed.

Conventionally, a nanostructure of such a device was made using atop-down method, in which a semiconductor thin film is grown and thenetched to leave a structure where it is needed. However, etching thesemiconductor thin film with this method cannot avoid physical andchemical damage to the deposited material caused by the process. Thiscritical problem with the conventional process serves as a hindrance tomaking active optical devices such as lasers.

As alternatives to this approach, bottom-up methods such as solutionreaction and electrochemical deposition reaction are being used to formnanostructures on a substrate. Methods for forming nano thin-films andnanostructures from the bottom up to form thin films of nanomaterials ona wafer include frame hydrolysis deposition (FHD), chemical vapordeposition (CVD), modified chemical vapor deposition (MCVD), physicalvapor deposition (PVD), sputtering, e-beam evaporation deposition, spincoating, and plasma surface treatment using microwaves.

Methods for forming nanostructures include atomic layer deposition(ALD), which involves synthesis in a vacuum atmosphere, and metalorganic chemical vapor deposition (MOCVD). These methods allow foruniform and stable growth of nanoparticles. However, the vapordeposition methods require expensive systems and complex process steps,and the ALD and MOCVD processes have stability problems because metalorganic sources, which are toxic and pyrophoric, are mainly used asprecursors.

Besides, hydrothermal synthesis, which involves synthesis in a solution,electrochemical deposition, chemical bath deposition (CBD), etc. may beused. These methods are advantageous in that the process is simple andcosts low compared to the aforementioned vacuum process, allows for easylarge-area deposition, and is relatively free from environmentalpollution and safety issues.

In addition, plasma surface treatment using microwaves is increasinglyused thanks to its short processing time, the ease of installation, itslow installation cost, and its efficiency and economic advantages.

FIG. 1 shows a conventional process of forming a nanostructure usingmicrowaves. In the conventional process of forming a nanostructure usingmicrowaves, the surface 5 of a processing object is processed by amicrowave generator 7 and an electrically conductive target 3. Themicrowave generator 7 includes a chamber 1. A magnetron, which generatesmicrowaves 2, is mounted at one side of the chamber 1, and a table 6 forthe target 3 and the processing object 4 to sit on is mounted in thechamber 1. Microwaves 2 are distributed within the chamber 1 and emittedto the target 3 by the operation of a stirrer 18. The target 3 may becomposed of metal, carbon, etc., for example.

However, deposition methods involving such a solution process havedifficulties in producing uniform materials due to changes inconcentration and reaction conditions caused by the evaporation of areaction solution during a reaction process.

Accordingly, there is a need to develop a novel processing device thatallows for the development of organic and inorganic materials based on asolution process that shows high reproducibility while keeping theconcentration of the reaction solution constant and that is simple andcosts low, in order to make up for the problems occurring in theconventional solution process.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide ananostructure formation device using microwaves that enables supply of asolution in real time by introducing a solution process factor to aconventional nanostructure formation device using microwaves and allowsfor the manufacture of stable materials by minimizing changes inconcentration of the solution caused by the evaporation of the solutionduring the process.

The present invention provides a nanostructure formation device usingmicrowaves, the device including: a chamber; a microwave generatormounted within the chamber; and a reaction container part contained inthe chamber including a reaction solution and a substrate.

FIG. 2 shows a nanostructure formation device using microwaves accordingto an exemplary embodiment of the present invention. As shown in FIG. 2,the nanostructure formation device using microwaves according to anexemplary embodiment of the present invention includes: a chamber 10; amicrowave generator 20 mounted within the chamber; and a reactioncontainer part including a reaction container 30 for containing areaction solution and the substrate 40.

In the nanostructure formation device using microwaves according to thepresent invention, the microwave generator 20 includes a magnetron thatgenerates microwaves, and the microwaves generated by the operation ofthe magnetron form a microwave field within the chamber. In thenanostructure formation device using microwaves according to the presentinvention, microwaves 20 for heating the substrate 40 immersed in asolution preferably have a frequency of 2.45 GHz and an intensity of 2kW or less.

The nanostructure formation device using microwaves according to thepresent invention may further include a reaction solution circulator forcirculating a reaction solution from a reaction solution reservoiroutside the chamber to a reaction container inside the chamber. In thenanostructure formation device using microwaves according to the presentinvention, the reaction solution circulator may further include anactuating pump.

FIG. 3 shows a nanostructure formation device using microwaves accordingto another exemplary embodiment of the present invention. As shown inFIG. 3, the nanostructure formation device using microwaves according toan exemplary embodiment of the present invention further includes areaction solution circulator including a reaction solution inlet 53 anda reaction solution outlet 52′, that is connected into the chamber tocirculate a reaction solution from a reaction solution 60′ reservoiroutside the chamber to the reaction container inside the chamber, and ametering pump 51.

The reaction solution circulator 50 is mounted outside the chamber, andperforms a circulation function to keep the concentration of thereaction solution in the reaction container constant. Also, the meteringpump 51 enables the formation of nanostructures on a large-areasubstrate by supplying a large quantity of reaction solution into thechamber.

In the nanostructure formation device using microwaves according to thepresent invention, the reaction solution circulator 50 includes areaction solution inlet pipe and a reaction solution outlet pipe thatare connected to the outside of the chamber.

In the nanostructure formation device using microwaves according to thepresent invention, the reaction solution inlet pipe and the reactionsolution outlet pipe are formed of an outer metal pipe and an innerTeflon pipe. The reaction solution inlet pipe and the reaction solutionoutlet pipe may prevent a reaction from proceeding before the reactionsolution reaches the substrate by inserting the Teflon pipe into theouter metal pipe to allow the outer metal pipe to stop microwavesemitted from inside from reaching the inner Teflon pipe.

In the nanostructure formation device using microwaves according to thepresent invention, the reaction container part 300 includes an upperreaction container 310, a substrate 40, and a lower reaction container320 that are sequentially stacked in a disassemblable or assemblablestate, wherein the portion where the bottom of the upper reactioncontainer 310 adjoins the substrate 40 includes an elastic body 330. Inthe nanostructure formation device using microwaves according to thepresent invention, the upper reaction container 310 includes: a verticalportion 312 having a vertical height to contain a reaction solution; anda tapered sloping portion 311 formed above the vertical portion 312.

The nanostructure formation device using microwaves according to thepresent invention may include a plurality of reaction containers forcontaining the reaction solution.

FIGS. 4 and 5 show a nanostructure formation device using microwavesaccording to another exemplary embodiment of the present invention. Asshown in FIGS. 4 and 5, the nanostructure formation device usingmicrowaves according to an exemplary embodiment of the present inventionfurther includes a plurality of reaction containers 30 and 31 within thechamber, for containing the reaction solution. Preferably, thenanostructure formation device using microwaves may further include aninner reaction solution circulator 70 for circulating a reactionsolution between each reaction container.

The nanostructure formation device using microwaves according to thepresent invention further includes an inner reaction solution circulator70 for circulating a reaction solution between the plurality of reactioncontainers.

In the nanostructure formation device using microwaves according to thepresent invention, the reaction container part 300 may further include aheating means for heating the substrate 40 included therein. In thenanostructure formation device using microwaves according to the presentinvention, the heating means is not specifically limited.

The nanostructure formation device using microwaves according to thepresent invention may further include a rotating plate for rotating thereaction container part 300.

FIG. 6 shows a nanostructure formation device using microwaves accordingto another exemplary embodiment of the present invention. As shown inFIG. 6, the nanostructure formation device using microwaves according toan exemplary embodiment of the present invention further includes astirrer 18, and the microwaves 20 may be distributed within the chamber10 by the operation of the stirrer 18.

The nanostructure formation device using microwaves according to thepresent invention allows for the manufacture of stable materials byconsistently maintaining the concentration of a reaction solution andthe process conditions for it when thin-film formation, surfacetreatment, and nanostructure manufacture, and chemical bath depositionare performed by using microwaves.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the inside of a chamber of a conventionalnanostructure formation device using microwaves.

FIGS. 2 through 6 are schematic views of the inside of a chamber of ananostructure formation device using microwaves according to the presentinvention.

FIG. 7 is a schematic view of the front part of the nanostructureformation device using microwaves according to the present invention.

FIG. 8 is a schematic view of a solution inlet pipe and solution outletpipe of the nanostructure formation device using microwaves according tothe present invention.

(a) of FIG. 9 is a schematic view showing a cross-section of a reactioncontainer part of the nanostructure formation device using microwavesaccording to the present invention, and (b) of FIG. 9 shows the realappearance of the reaction container part. (b-1) is top plan explodedview and bottom exploded view of the reaction container part, and (b-2)is a top plan view, perspective view, and bottom perspective view of thereaction container part.

FIGS. 10 to 11 are SEM analysis images of ZnO nanorods synthesized byusing the nanostructure formation device using microwaves according tothe present invention and ZnO nanorods synthesized by traditionalsynthesis methods.

(a) of FIG. 10 is an SEM analysis image of ZnO nanorods synthesized byusing the nanostructure formation device using microwaves according tothe present invention, and (b) and (c) are SEM analysis images of ZnOnanorods synthesized by a traditional hydrothermal synthesis method, and(a) of FIG. 11 is an SEM analysis image of ZnO nanorods synthesized by atraditional atomic layer deposition method, (b) is an SEM analysis imageof ZnO nanorods synthesized by a traditional hydrothermal synthesismethod, (c) is an SEM analysis image of ZnO nanorods synthesized by atraditional chemical bath deposition method, and (d) is an SEM analysisimage of ZnO nanorods synthesized by a modified chemical bath depositionmethod.

FIG. 12 is SEM analysis images of a Fe₂O₃ nano thin film formed by usingthe nanostructure formation device using microwaves according to thepresent invention and a Fe₂O₃ nano thin film synthesized by atraditional hydrothermal synthesis method.

(a) of FIG. 12 is an SEM analysis image of a Fe₂O₃ nano thin film formedby using the nanostructure formation device using microwaves accordingto the present invention, and (b) is an SEM analysis image of a Fe₂O₃nano thin film synthesized by a traditional hydrothermal synthesismethod.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an exemplary embodiment of the present invention will bedescribed in more details. However, the present invention is not limitedby the following embodiment.

<Exemplary Embodiment> Manufacture of Nanostructure Formation DeviceUsing Microwaves

FIGS. 7 through 9 show a nanostructure formation device using microwavesthat is manufactured according to an exemplary embodiment of the presentinvention.

As shown in FIG. 7, the nanostructure formation device using microwavesthat is manufactured according to an exemplary embodiment of the presentinvention includes a chamber 100, and a microwave feeder 110 and atemperature controller 120 that are formed outside the chamber.

Moreover, as shown in FIG. 8, the nanostructure formation device usingmicrowaves that is manufactured according to an exemplary embodiment ofthe present invention includes a reaction solution inlet pipe 52′ and areaction solution outlet pipe 53 that are connected to the outside ofthe chamber.

FIG. 9 shows a reaction container part 300 used in the nanostructureformation device using microwaves that is manufactured according to anexemplary embodiment of the present invention. As shown in FIG. 9, thereaction container part 300 according to an exemplary embodiment of thepresent invention includes an upper reaction container 310, a substrate40, and a lower reaction container 320 that are sequentially stacked ina disassemblable or assemblable state, wherein the portion where thebottom of the upper reaction container 310 adjoins the substrate 40includes an elastic body 330, and, when the upper reaction container310, the substrate 40, and the lower reaction container 320 areassembled after being stacked, the elastic body 330 serves as a gasketso that a reaction solution is contained in a vertical portion 312 ofthe upper reaction container.

<Test Examples> Formation of Nanostructure Using Nanostructure FormationDevice Using Microwaves

Test Example 1: Efficiency (Growth Rate) Analysis of ZnO NanorodSynthesis Process Using Microwaves

ZnO nanorods were synthesized by using the nanostructure formationdevice using microwaves manufactured according to an exemplaryembodiment, and ZnO nanorods were synthesized by traditionalhydrothermal synthesis methods. The growth rate for each synthesisprocess was analyzed and the results were tabulated in Table 1 below.

TABLE 1 Process efficiency of traditional Test Example 1 hydrothermalsynthesis methods Process method Microwave-chemical HydrothermalHydrothermal bath deposition synthesis synthesis Process 15 mins 12hours 20 hours time Nanorod App. 453 nm App. 1,500 nm App. 1,000 nmlength Nanorod App. 64 nm App. 150 nm App. 40 to 80 nm diameter Growth1,812 nm/hour 125 nm/hour 50 nm/hour rate

As shown in Table 1, the ZnO nanorod synthesis process using thenanostructure formation device using microwaves manufactured accordingto an exemplary embodiment of the present invention showed a largeincrease in growth rate (nanorods synthesized per hour), in comparisonwith the ZnO nanorod synthesis processes using traditional hydrothermalsynthesis methods, and it can be seen that, in comparison with thetraditional hydrothermal synthesis methods, the process time was greatlyreduced but the process efficiency was definitely increased.

The SEM analysis images of the ZnO nanorods synthesized by theaforementioned synthesis processes are depicted in FIG. 10.

Test Example 2: ZnO Nanorods (Full Width at Half Maximum Analysis)

The full width at half maximum of ZnO nanorods synthesized by using thenanostructure formation device using microwaves manufactured accordingto an exemplary embodiment, and the full width at half maximum of ZnOnanorods synthesized by traditional synthesis methods such as atomiclayer deposition (ALD), hydrothermal synthesis, chemical bath deposition(CBD), and modified chemical bath deposition (M-CBD) was analyzed andthe results were tabulated in Table 2 below.

TABLE 2 Test Example 2 Traditional synthesis methods Process methodMicrowave-chemical Atomic layer Chemical solution Modified chemical bathdeposition deposition Hydrothermal deposition bath deposition (MC-CBD)(ALD) synthesis (CBD) (M-CBD) Full width at 0.15~0.18 0.3~0.4 0.16~0.320.35~0.44 0.18~0.21 half maximum

As shown in Table 2, the ZnO nanorods synthesized by using thenanostructure formation device using microwaves manufactured accordingto an exemplary embodiment of the present invention showed a decrease inXRD full width at half maximum, in comparison with the ZnO nanorodssynthesized by the traditional synthesis methods.

The decrease in full width at half maximum means that the particles havehigh crystalline quality. Accordingly, it can be seen that the ZnOnanorods synthesized by using the nanostructure formation device usingmicrowaves manufactured according to an exemplary embodiment of thepresent invention have excellent crystalline quality.

The SEM analysis images of the ZnO nanorods synthesized by theaforementioned synthesis processes are depicted in FIG. 11.

Test Example 3: Efficiency (Growth Rate) Analysis of Fe₂O₃ Nano ThinFilm Synthesis Process Using Microwaves

A Fe₂O₃ nano thin film was synthesized by using the nanostructureformation device using microwaves manufactured according to an exemplaryembodiment, and a Fe₂O₃ nano thin film was synthesized by traditionalhydrothermal synthesis methods. The growth rate for each synthesisprocess was analyzed and the results were tabulated in Table 3 below.

TABLE 3 Process efficiency of traditional hydrothermal Test Example 3synthesis methods Process method Microwave-chemical HydrothermalHydrothermal Hydrothermal bath deposition synthesis synthesis synthesisProcess time 10 mins 4 to 24 hours 2 hours 12 hours Thin film thickness40 nm 120 nm 100 nm 10 nm Growth rate 2,400 nm/hour 29.9 nm/hour 50.04nm/hour 0.83 nm/hour

As shown in Table 1, the Fe₂O₃ nano thin film synthesis process usingthe nanostructure formation device using microwaves manufacturedaccording to an exemplary embodiment of the present invention showed alarge increase in growth rate (nanorods synthesized per hour), incomparison with the Fe₂O₃ nano thin film synthesis processes usingtraditional hydrothermal synthesis methods, and it can be seen that, incomparison with the traditional hydrothermal synthesis methods, theprocess time was greatly reduced but the process efficiency wasdefinitely increased.

The SEM analysis images of the Fe₂O₃ nano thin films synthesized by theaforementioned synthesis processes are depicted in FIG. 12.

The nanostructure formation device using microwaves according to thepresent invention allows for the manufacture of stable materials byconsistently maintaining the concentration of a reaction solution andthe process conditions for it when thin-film formation, surfacetreatment, and nanostructure manufacture, and chemical bath depositionare performed by using microwaves.

1. A nanostructure formation device using microwaves, the devicecomprising: a chamber; a microwave generator mounted within the chamber;and a reaction container part contained in the chamber comprising areaction solution and a substrate.
 2. The nanostructure formation deviceof claim 1, further comprising a reaction solution circulator forcirculating a reaction solution from a reaction solution reservoiroutside the chamber to a reaction container inside the chamber.
 3. Thenanostructure formation device of claim 2, wherein the reaction solutioncirculator comprises a reaction solution inlet and a reaction solutionoutlet.
 4. The nanostructure formation device of claim 3, wherein thereaction solution circulator further comprises an actuating pump.
 5. Thenanostructure formation device of claim 3, wherein the reaction solutioncirculator comprises a reaction solution inlet pipe and a reactionsolution outlet pipe that are connected to the outside of the chamber.6. The nanostructure formation device of claim 5, wherein the reactionsolution inlet pipe and the reaction solution outlet pipe are fainted ofdouble pipes consisting of an outer metal pipe and an inner Teflon pipe.7. The nanostructure formation device of claim 1, wherein the reactioncontainer part comprises an upper reaction container, a substrate, and alower reaction container that are sequentially stacked in adisassemblable or assemblable state, wherein the portion where thebottom of the upper reaction container adjoins the substrate comprisesan elastic body.
 8. The nanostructure formation device of claim 7,wherein the upper reaction container comprises: a vertical portionhaving a vertical height to contain a reaction solution; and a taperedsloping portion formed above the vertical portion.
 9. The nanostructureformation device of claim 1, comprising a plurality of reactioncontainer parts within the chamber.
 10. The nanostructure formationdevice of claim 9, further comprising an inner reaction solutioncirculator for circulating a reaction solution between the plurality ofreaction container parts.
 11. The nanostructure formation device ofclaim 1, comprising a microwave feeder and a temperature controller thatare formed outside the chamber.